Roasting-furnace.



N0. 685,344. Patnfd 061.29, |90l.

E. B. `PARNELL.

STING FURNACE.

ppncaeim med :my 1e, 159m (No Model.)

UNITED STATES PATENT OFFICE.

' ELIZABETH EA'E-ns'rony PAENELL, oE oARsIIALToN, ENGLAND.

fEoAsrl'NG-FURNACE.;

SPECIFICATION forming part of Letters rates/c 10.685,344, dated otobef29, 1901.

riginal application led Jailguary 3, 18928, Serial: No. 665,381. Divided,and this a No. 717,044.. (No model.)

T0 all whom, t may concern:

Be it known that I, ELIZABETH BAENsToN PARNELL, a subject of the Queenof England, residing at Carshalton county of Surrey, Eng land-,haveinvented a certain new and useful Roasting-Furnace, of which thefollowing is a specification.

This invention relates to an improved construction of furnace for use inroasting ores for the recovery therefrom of metals, and this applicationis a division of my pending application, filed January 3, 1898, SerialNo. 665,381.

The furnace according to this invention is so constructed as to becapable of being employed as well either as a muiile or a reverberatoryfurnace, or simultaneously as a muffle and a reverberatory furnace.

The furnace' may be constructed from iron plates bolted together andarranged, preferably, to form a triangle in section (though I do notconfine myself to this form) and adapted to carry a half-mufde hearth.The upper angle forms a flueway for the fumes evolved from the roastingore. The two lower angles form ues for the fire, which thus passes oneach side to the stack.

The furnace can be converted to a reverberatory by directing the flameover instead of beneath the hearth.

Figure 1 is a longitudinal section of a furnace on the line 1 1 of Fig.2; Fig. 2, atransverse section of the furnace shown in Fig. 1 on theline 2 2 of Fig. 1; Fig. 3, Van elevation, and Fig. 4. a plan, of a plowused in conjunction with the furnace.

With reference rst to Figs. 1 and 2, A is a shell, built conveniently ofcast-iron, forniing a housing, triangular in cross-section, for thehearth, a lire-grate and bridge being provided at A8 and A9,respectively. The hearth 1 is shown at B, extending for the greater partof the length of the housing A, and is preferably of curved form intransverse cross-section, as shown in Fig. 2. The hearth thus dividesthe space Within the shell into long compartments or flues-three in thiscaseand one of the most important features ofthis construction is thatthe furnace can be Inade to act as either a mue or a reverberatoryfurnace by directing the fire either along the @Imation niet May16,1899. serai two flueslnarke'd A or along the upper one marked A2; orthe furnace may belused si. inultaneously as a muffle and areverberatory furnace-41. e., the iame may be directed over the chargeat the same time that heat from the fire is being directed under thehearth along the two lower flues. I have found this lastmethod of usingthe furnace of very great efficacy in the roasting of ores giving oft'arsenical and other volatile or easily-oxidizable fumes. The directionof the heat or flame from the lire along the upper flue may be effectedbyopening a damper A10, hinged at A11 to a support A12, the lower fluesAbeing closed by a damper A12, similarly pivoted at A11. It is thusobvious that to pass the heat or flame from the furnace along the fluesA it is only necessary to open the damper A13 and close the damper A10and that by opening both dampers together the heat or flame may becaused to pass through the flues A' A2 simultaneously. Between thefire-grate and the iiues is the usual chamber B for supplying heated airto perfect combustion at the rear of the furnace. The air enters thechamber by the passage B2 and makes its exit at B2. Above this chamberis arranged a vertical damper B4 for regulating the draft of the furnacein the usual well-known manner. The shell, whose iron walls are letteredat d, has preferably a suitable lining, as shown at a',

and the whole shell may be 'conveniently mounted on brickwork, such amounting being shown in the drawings and lettered C. The charge of orealready treated, say, with chromic acid is fed onto the hearthB througha hopper A2 (seen in Fig. 1) and is caused to slowly travel the wholelength of the hearth, on reaching the end ofv which it is dischargedinto wagons or other receptacles provided. Suitable sight-holes areprovided at intervals in the length of the furnace, as are shown at A6.The means adopted to convey the charge through the furnace may be of anywellknown kind; but I prefer a conveyer of the following specialconstruction.

One or more endless chai-ns, preferably of cast-iron and having ploWs orconveyers at tached, pass along the hearth from end to end. One suchchain is shown at D. At each end Where the chain. emerges from the furnace it passes over a chain-wheel D', one of which is caused to rotateand drag the chain in a direction from the hopper end to the deliveryend of the hearth. A return-way for the chain is provided in thebrickwork at C', during passage through which itbecomes Well cooled. Thechain has attached to it at various points plows or conveyers adapted tothoroughly stir and turn the charge Without carrying it too rapidlythrough the furnace. The plows are shown at D2 in Figs. l and 2, and oneis shown to a larger scale in Figs. 3 and 4. In these two gures ddesignates wings of the plow, which are the most effective part of thedevice in bringing fresh portions of the charge to the surface. Thespeed at which the plows move through the charge may be varied to suitdifferent kinds of ores requiring roasting for different periods, theusual time required when the ore has been prepared as hereinbeforedescribed being eight to ten hours.

Provision is made in this furnace for the copious admission of wet steamthrough nozzles or holes placed as near to the hearth as convenientlypossible, so that the steam can play upon the charge during the processof roasting, the steam being required for the formation of snlfates. Oneform of nozzle is shown in the drawings, Figs. l and 2, at A4, beingconnected to a steam-pipe A5, extending along both sides of the shell onthe outside. The ore should not be heated to a higher temperature thanis necessary for the formation of sulfates. When the roasted ore hasbeen discharged into the wagons or other receptacles, it may be groundand again roasted or may be at once treated with alkali, if requiringsuch treatment, and transferred direct to an extractor. The triangularform of furnace is of value as lending itself to transport, it beingcapable of being packed in small space. The most important feature,however, in the construction of the furnace and to which particularattention is directed is that the sides a a' are flat and inclinedtoward one another, so that an apex is formed which may be either asharp angle or, as shown in the drawings, slightly rounded. The objectof this construction is to give a greater depth to the zones or layersof different temperatures known to exist in furnaces. It is easilyunderstood that in a furnace with vertical sides connected at the top byan arch or even in the case of a furnace built in the form of asemicircle from the hearth the different zones of heat must be very muchcontracted in depth, as they will all occupy the space at the extremetop of the oven; but by contracting the upper part of the furnace, as inthe arrangement described, the separate zones will be forced to take aposition below one another, each occupying a distinct part of thefurnace. This has been found of great advantage in dealing with orescontaining arsenic, in that as fumes rise from the ore they pass throughthe dilferent zones of heat until, reaching the highest point of thefurnace, Where the hottest gases are collected, they are thoroughlypuriiied,and when drawn off may be readily condensed.

I claiml. In a roasting-furnace, the combination of a longitudinalhousing A, of triangular transverse section rounded at the top or apex,a hearth B dividing the housing throughout its length into upper andlower chambers A2 A' respectively, means of communication between oneend of each fiue and a common source of heat and a chain conveyerarranged along the length of the hearth, substantially as set forth.

2. In a roasting-furnace, the combination of a longitudinal housing A oftriangular transverse section having a rounded top or apex, a hearth Bdividing the housing throughout its length into upper and lower chambersor lues A2A respectively, means of communication between one end of eachflue and a common source of heat, a damper between the end of the flueA2 and the source of heat, a damper between the Hue A and the source ofheat, and a chain con veyer arranged along the length of the hearth,substantially as described.

In testimony whereof I have hereto set my hand in the presence of thetwo subscribing witnesses.

ELIZABETH BARNSTON lAltNELL.

Witnesses:

HAROLD WADE, HARRY S. RIDGLY.

